As early as the seventeenth century these _glas-schleifer_ were divided into several more or less independent groups. The _eckigräber_ did the coarser work. It fell to them, in the first place, to remove all irregularities on the surface of the glass—for example, the rough projections left on the foot where the pontil had been attached—and more especially to make the cross cuttings required to form the facets, which at a later time were so much in vogue. The _kugler_ were another class of workmen, who prepared the shallow circular or oval pits which play so important a part in the decoration. The work of the actual engraver belongs more to the domain of art. The cutting in this case is effected by a little wheel of copper from a quarter inch to an inch in diameter, revolving rapidly at the end of a horizontal spindle, moved by a treadle. These little copper wheels are of various forms, and not the least part of the skill of the artist lies in the selection of the form most suitable for the work in hand. The decision as to the depth of the engraved line, and again as to which part should be polished and which left dull depends also upon his judgment. His difficulties are increased by the fact that he is unable to follow the progress of the work in hand, for not only has he to press the glass against the under surface of the wheel, but the part of the surface on which he is working remains covered by the emery or other abrading material employed (Von Czihak, pp. 136-139). It will be noticed that as a rule the incised parts are left unpolished and dull as they come from the wheel, and that the polishing is reserved for the little circular depressions, the _kugeln_, which then show out like jewels cut _en cabochon_. We are apt to associate this engraved glass with Bohemia, but to say nothing of the highly finished and artistic work done at Nuremberg and Regensburg, it is probable that in no other district has the engraving and cutting of glass become so much a distinct industry as in the Silesian valleys that descend from the highest peaks of the Riesengebirge towards the town of Hirschberg. As early as the commencement of the seventeenth century we come across an Italian engraver on rock crystal in the service of the Freiherr von Schaffgotsch at Schloss Kynast, and at the same spot towards the end of the century, in the employ of the same family, we find Friedrich Winter, who has the credit of being the first in this district to apply water-power to the cutting and polishing of glass.